1. Field of the Invention
This invention relates to a dielectric resonator device and, in particular, to a construction for temperature compensation of a dielectric resonator device.
2. Description of the Prior Art
Recently, the development of dielectric materials has advanced so remarkably, that it has been possible to obtain dielectric materials having a small loss angle or tan .delta. and for which the temperature characteristic of the dielectric constant can be controlled in either the positive or negative direction. Also, the use of dielectric materials as resonators having simple construction has been investigated.
The principles of dielectric resonators have long been known in the field, as described for example, in "PROCEEDINGS OF THE IRE", Oct., 1962, page 2081-2092. The Dieletric Microwave Resonator by A. OKAYA and L. F. BARASH".
A dielectric resonator can be made from a piece of dielectric material having a cylindrical or rectangular solid shape. The resonant frequency thereof is determined by the dielectric constant, the dimensions and the shape of the resonator.
In comparison with metal cavities which have been used as microwave resonators, a dielectric resonator has many advantages such as its miniature size, low loss, insensitivity to magnetic DC biasing fields and its ability to concentrate large RF magnetic fields in small volumes.
However, a dielectric resonator has a few disadvantages such as the changeability of the resonant frequency due to the temperature dependency of the dieletric constant, and the difficulty of economically manufacturing a large number of uniform dielectric pieces, Accordingly, it is necessary to compensate for the resonant frequency variation or shift due to variations in temperature.
There are a few known methods of compensating for the resonant frequency variation due to temperature, one of which provides a heat sink near the dielectric resonator element, another of which comprises an element having a small thermal coefficient made from different kinds of dieletric materials.
However, these conventional methods are not always practical from a viewpoint of economy, simplicity or accuracy of the device.